Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• explained by the protonation of ring tautomers 9 to 10 (Scheme 4), followed by a water elimination, and subsequent deprotonation of cations 11 to afford isoindoles 4 [3][4][5]. The protonation of the latter [6], followed by the attack of water at position 1 of cations 12, and subsequent deprotonation of

• formation of the dimer-like products 3a and 3b can be rationalized by the electrophilic attack of cations 12a,b at position 3 of isoindoles 4a,b to give cations 15a,b (Scheme 5). The reaction of the latter with water, followed by deprotonation leads to dimer-like compounds 16a,b, being the ring tautomers of

• the isolated products 3a and 3b. On the contrary, the formation of dimer-like products 8a and 8b can be explained by the electrophilic attack of cations 11c,d at position 1 (instead of position 3) of isoindoles 4c,d to afford cations 17a,b (Scheme 6), which transform to the dimer-like products 5a,b

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• aromatization of the polycyclic intermediates provides the corresponding polycyclic pyrrolo-isoindoles and isoindolo-pyrrolo-indoles. A theoretical study on the stereoselective Diels–Alder reactions, carried out by calculating the endo/exo transition states, revealed the assistance of non-covalent interactions

• simplest pyrrole-fused heterocyclic aza-bridged compounds. The numerous series of pyrrolizine-containing polycycles include pyrrolo[2,1-a]isoindoles [6], pyrrolo[1,2-a]indoles [7][8][9][10] and isoindolo[2,1-a]indoles [11] (Figure 1). These three series constitute the core of natural occurring alkaloids

• the solvent at 100 °C afforded pyrrolo[2,1-a]isoindoles 18a–c in good yields. This annulation process was regioselective, showing a preference of the cross-coupling reaction with the C-5 pyrrolic position and not with the vinyl moiety, which would give the dihydropyrrolo[1,2-b]isoquinoline 19. A

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• . This transformation proceeds via a 1,3-dipolar cycloaddition between the in situ formed azomethinylide 15 and the benzoquinone 16 to directly give 17 (Scheme 1). Spontaneous oxidation of the so-obtained cyclization adduct generates isoindole 18. Isoindoles have also found application as dyes. Pigment

• yellow 139 (12), which is sold by BASF as Paliotol® Yellow K 1841 belongs to the class of highly resistant and effective 1,3-disubstituted isoindoline dyes. Recently, the use of isoindoles as red to near-infrared fluorophores was reported [12]. Another interesting isoindole-based dye, 25, arises from the

Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

• Kristina Butković,
• Željko Marinić,
• Krešimir Molčanov,
• Biserka Kojić-Prodić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2011, 7, 1663–1670, doi:10.3762/bjoc.7.196

• % yield). Keywords: [3 + 2] cycloaddition; isoindoles; nitrile imines; pyrazoles; sydnones; Introduction Sydnones belong to the group of five-membered heterocyclic compounds referred to as being "mesoionic" and have been widely studied since their discovery [1][2][3][4][5]. They can be represented as

• of isomers, resulted in the formation of two products in the same mutual ratio, along with large amounts of unidentified high-molecular-weight products. Separation by column chromatography in combination with thin layer chromatography gave dihydropyrazolo-isoindoles, 11 (12.5%) and 12 (5%) (Scheme 3

Desymmetrization of 7-azabicycloalkenes by tandem olefin metathesis for the preparation of natural product scaffolds

• Wolfgang Maison,
• Marina Büchert and
• Nina Deppermann

Beilstein J. Org. Chem. 2007, 3, No. 48, doi:10.1186/1860-5397-3-48

• -azabicycloalkenes by intra- and intermolecular tandem metathesis sequences with ruthenium based catalysts. Conclusion Desymmetrization of 7-azabicycloalkenes by olefin metathesis is an efficient process for the preparation of common natural product scaffolds such as pyrrolidines, indolizidines and isoindoles

• intramolecular RORCM or intermolecular ROCM sequences to give a range of common natural product scaffolds such as pyrrolidines, indolizidines and isoindoles. The protocols use readily available starting materials, are simple and give densely functionalized metathesis products ready for further manipulations